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Water is the major factor limiting crop production in western Kansas due to declining groundwater levels in the Ogallala aquifer resulting from withdrawals for irrigation exceeding recharge rates coupled with erratic semi-arid rainfall. Study objectives were to assess yield and water productivity of water limited cropping systems in western Kansas using DSSAT-CSM (Decision Support System for Agrotechnology Transfer Cropping Systems Model). The cropping systems evaluated included continuous (corn, wheat, and grain sorghum) and rotation (corn-wheat, corn-wheat-grain sorghum, and corn-wheat-grain sorghum-corn). Results showed that the model adequately reproduced measured days to flowering and maturity as well as yield and aboveground biomass of all three crops. Crop rotation improved water productivity of corn. Under deficit irrigation, corn in rotation produced higher yields, crop water productivity, and irrigation water use efficiency compared to continuous corn, implying that crop rotation is a better option under limited well capacities. Under full irrigation, yield and water productivity of continuous wheat were lower than wheat in rotation. In contrast, continuous wheat yields under deficit irrigation were better than under crop rotation. Deficit irrigation substantially improved irrigation water use efficiency of grain sorghum under both continuous and crop rotations. Long–term average grain sorghum yields under rotation were higher than those of continuous grain sorghum. Indicating grain sorghum should be grown in rotation under deficit irrigation. This research did not simulate the impacts of pests, weeds and diseases, hail and freeze damage on crop yield. However, the study identifies cropping systems that are more likely to produce highest water productivity under semi-arid climate similar to that in western Kansas. [ABSTRACT FROM AUTHOR]

The sustainability of winter wheat (Triticum aestivum L.) − summer maize (Zea mays L.) rotation (W − M), which is commonly practiced in the North China Plain (NCP), is threatened by severe groundwater deficits and environmental pollution due to excessive nitrogen (N) applications. Considering the need for protein-rich forages by local livestock operations and the environmental benefits of growing perennial legumes, we propose that an alfalfa (Medicago sativa L.)-based system is worth introducing for field practice in the NCP. An integrated evaluation was used in this four-year study to compare the agronomic, economic, and environmental performances of the following four cropping patterns: alfalfa monoculture (AA), alfalfa and silage maize intercropping with or without N input which is designed for local climate condition, maize monoculture with or without N input which is much-discussed as a resources-saving substitution and commonly practiced W − M. W − M obtained the highest aboveground dry matter (DM) productivity (P < 0.05) based on the highest irrigation water and N fertilizer consumption (P < 0.05) which caused considerable soil mineral N (Nmin) accumulation. The production cost of maize monoculture was the lowest as well as the DM yield, nitrogen accumulation and the net revenue compared with other systems (P < 0.05), moreover, there was a great risk of N losses during the offseason period. The alfalfa and silage maize intercropping with a low N input (120 kg ha−1 which is close to local practice for maize season) achieved 26.6%–34.9% more DM yield compared with AA and maize monoculture, and 12.5%–163.9% more N output compared with W − M and maize monoculture during four experimental years with same total economic revenue as W − M and AA did. The N input in alfalfa and silage maize intercropping dramatically improved the system productivity by assisting intercropped maize growth while did not lead to excessive Nmin accumulation within 0–210 soil layer compared with the intercropping system without N addition. The planting of alfalfa would not affect the water storage in the 0–60 soil layer after maize harvesting each year. For the effects of interspecific competition, the production of the intercropped alfalfa and maize was significantly decreased in 2020 and a three-year period of production is recommended for optimal use of the alfalfa and silage maize intercropping. Alfalfa and silage maize intercropping with an appropriate N input, which acquired comprehensive performances in terms of productivity, environmental impacts as well as economic profits, would be an optimal alternative system in the NCP. The alfalfa and silage maize intercropping with an appropriate N input (A + M), which achieved high dry matter yield, nitrogen uptake and net revenue with the lowest irrigation water and nitrogen fertilizer use, would be an optimal alternative system in the North China Plain. [Display omitted] • The wheat–maize rotation (W – M) in the North China plain is profitable but has inevitable negative environmental impacts. • Alfalfa and maize intercropping (A + M) was proposed for the high protein productivity and the adaptability to climate. • The agronomic, economic, and environmental performances were compared among A + M, W – M, and monoculture systems. • A + M was more productive than monoculture, and consumed lower groundwater and nitrogen than W–M without net revenue loss. • A + M would be an optimal alternative system in the North China Plain for its comprehensive performances. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural system models are potential tools for evaluating soil-water–nutrient management in intensive cropping systems. In this study, we calibrated and validated the Root Zone Water Quality Model (RZWQM) with both a generic plant growth module (RZWQM-G) and the CERES plant growth module (RZWQM-C) for simulating winter wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping systems in the Northern China Plain (NCP), China. Data were obtained from an experiment conducted at Yucheng Integrated Agricultural Experimental Station (36°57′N, 116°36′E, 28m asl) in the North China Plain (NCP) from 1997 to 2001 (eight crop seasons) with field measurements of evapotranspiration, soil water, soil temperature, leaf area index (LAI), biomass and grain yield. Using the same soil water and nutrient modules, both plant modules were calibrated using the data from one crop sequence during 1998–1999 when detailed measurements of LAI and biomass growth were available. The calibrated models were then used to simulate maize and wheat production in other years. Overall simulation runs from 1997 to 2001 showed that the RZWQM-C model simulated grain yields with a RMSE of 0.94Mgha−1 in contrast to a RMSE of 1.23Mgha−1 with RZWQM-G. The RMSE for biomass simulation was 2.07Mgha−1 with RZWQM-G and 2.26Mgha−1 with RZWQM-C model. The RMSE values of simulated evapotranspiration, soil water, soil temperature and LAI were 1.4mm, 0.046m3 m−3, 1.75°C and 1.0 for RZWQM-G and 1.4mm, 0.047m3 m−3, 1.84°C and 1.1 for RZWQM-C, respectively. The study revealed that both plant models were able to simulate the intensive cropping systems once they were calibrated for the local weather and soil conditions. Sensitivity analysis also showed that a reduction of 25% of current water and N applications reduced N leaching by 24–77% with crop yield reduction of 1–9% only. [Copyright &y& Elsevier]

China, as one of the largest food consumers in the world, is currently experiencing obvious impacts of climate change. Exploring the impact of climate change on the production potential of maize, wheat, and rice in China is of great significance in adapting to climate change and safeguarding global food security. In this study the Global Agro-Ecological Zone (GAEZ) model and the Extreme-Point Symmetric Mode Decomposition (ESMD) model were used to explore the trends in production potential of China's three major crops in the context of climate change from 1960 to 2010. There was a quasi-3-year and quasi-5-year cycle in changes in maize, wheat, and rice production potential due to climate change in China. Climate change increased maize and rice production potential and reduced wheat production potential. The increase in minimum temperature was the main reason for the increased maize and rice production potential. Reduced wheat production potential was mainly caused by increased maximum temperature. Decreases in precipitation had a substantial negative impact on the production potential of all three crops. These results suggest that priority should be given to adjusting the structure of agricultural cultivation and appropriately expanding the planting area of maize and rice to adapt to climate change. Accelerating the construction of agricultural infrastructure to reduce the negative impact of declining precipitation and increasing daytime temperature on agriculture is also a high priority in order to safeguard food security. • Climate change increased maize and rice production potential of China • Increased minimum temperature was the primary reason for increased yields • Wheat production potential decreased mainly because of maximum temperature stresses • There was a quasi-3&5-year cycle in changes in crop production potentials [ABSTRACT FROM AUTHOR]